The Warden program scans your computer for illegal processes that are influencing the game (speed hacks, bots, etc. has been decried as and evil 'breach of privacy' by some players (those who're running those bots and hacks, most likely). Most of their arguments are just whines from people who hate having their 'freedom' to cheat forcefully denied. Scott sums it up:

But the real bottom line: if you don’t like Warden and find it an invasion of privacy, vote with your pocketbook and don’t pay for WoW. It’s really that simple. Histrionics on message boards aside, playing WoW is not some kind of constitutional right, it’s a contract between you and Blizzard. As part of that contract, Blizzard is going to be looking over your shoulder while you’re playing. If you’re not OK with that, there are, believe it or not, other online games out there, some of which have been rumored to resemble WoW to varying degrees.

Game developers have not only the right, but the expected duty, to enforce a clean and open playing field. As black hats get better at breaking them, white hats are going to get sneakier (and sometimes overbearing) in protecting them. The arms race will never end.